Large internal gains that can be obtained in wide band gap semiconductors-based (GaN and ZnO types) Schottky and/or metal-semiconductor-metal photodetectors are generally accompanied by large dark current and time response. We show that, using quasi-alloy of BGaN/GaN superlattices as the active layer, the dark current can be lowered while maintaining high internal gain (up to 3 × 10⁴) for optical power in the nW range and low time response (few tens of ns) for optical power in the W range. Furthermore, the boron incorporation allows the tuning of the cutoff wavelength.